I'll do my own humorous summary
"Debating with an atheist"
Atheist: I deny the existence of air
Facilis: what?? You're breathing now. Air is the necessary precondition for breathing.
A: No. I see no reason why air is necessary for breathing. I am breathing now and i don't believe in air.
F: It the impossibility of the contrary. What else could you be breathing.
A: That is just an air of the gaps fallacy.You just insert air into the gaps since you do not know how people breathe.
F:But how else can you account for breathing?
A:I'm just breathing because that is the way it is. I'm still going to deny the existence of air.

Air (or rather oxygen) is easy to prove.
Put a lit candle into a small enclosed compartment and will go out after a while, proving that there was some gaseous stuff in the compartment that the fire needed to burn (and which was used up by the fire).
Put a small animal (a rat for example) into a small compartment and after a while it will suffocate (or rather, drop unconscious) showing that there probably was some invisible stuff in the compartment which was needed by the rat for survival (well, to be more exact it is 2 stuffes, O2 which is needed and the produced CO2 which is harmful).
Put a plant (thatv is big enough) together with the rat into an enclosed compartment and you can even show, that plants obviously produce the stuff that is needed by animals for their survival.
As for the air that surrounds us...
it might be invisible, but we see the effect it has in the form of wind.
So, there is not a single jota of faith needed to accept the existence of air/oxygen.

F: It the impossibility of the contrary. What else could you be breathing.
A: That is just an air of the gaps fallacy.You just insert air into the gaps since you do not know how people breathe.
F:But how else can you account for breathing?

Um. Are you suggesting that we don't actually know why we need air to breathe and that air is only necessary because we can't think of any other theories?

Just because you failed primary school biology and chemistry doesn't mean everybody else did too.